This invention pertains to magnetic disk storage devices and more particularly to actuators for such devices where the permanent magnets associated with the actuator drive motor are isolated from the head-disk enclosure.
The accepted and most effective device for driving a magnetic disk drive actuator is a voice coil motor. One component of the voice coil motor is the permanent magnet that establishes the flux field in the gap in which the voice coil is driven. As faster access times are sought the permanent magnets are made increasingly stronger to enhance the flux field in the air gap. The fields about both the permanent magnet and the voice coil must be shielded from the disk enclosure where the transducer reads and writes minute magnetic domains at the data surface of the disk. The other problem presented by the permanent magnet is the possibility that particulate contamination might be released from the material of such strong magnets. Any particulate material from the magnet must be excluded from proximity with the disk data surface to avoid not only the head crash that is induced by a particle that has a size exceeding the fly height of the transducer head, but also the destructive effects of strong magnetic particles on the data surface that would cause extensive, unretrievable alterations and erasures.